Test of the variant of the Stokes–Einstein relation described by D ∼ τ⁻¹ for Na⁺, K⁺, Rb⁺ and their corresponding Cl⁻: (a) Na⁺, K⁺and Rb⁺, (b) data for alkali ion corresponding Cl⁻. The symbols are the simulated data and the solid lines are fitted by D ∼ τ^−ξ. The colored exponent ξ is corresponding to the same colored solid line. The data of alkali ion corresponding to Cl⁻ in (b) is plotted in the same color as shown in (a).